32a EXPERIMENT STATION. [Jan. 



during business hours each day, thus preventing him from 

 carrying on the experimental work necessary during that period 

 of the year. The summer farmers' week also consumed much 

 time, when it was needed and really belonged elsewhere, so 

 that the actual station work has suffered severely. 



In addition, there is a large and increasing demand for the 

 fumigation of rooms, and even entire houses, for the destruction 

 of household pests. This is work which is so dangerous, 

 because of the poisonous gas used, that it should never be 

 done except by those having had experience, and for that 

 reason treatments of this nature have been made by members 

 of the department. Still, it subtracts from the time available 

 for the regular station work. 



In spite of the interferences above indicated some work has 

 been accomplished. A part of the correspondence has shown 

 that unknown insects were causing injury, and also that old 

 pests were working in new ways, and the investigation of such 

 cases is legitimate station work. Examples of this are: several 

 instances where the European corn borer was reported as work- 

 ing far outside its known limits of infestation; and the out- 

 break of the green clover worm (Plathypena scabra Fab.) on 

 beans, which seemed to call for the immediate testing of 

 various methods of control. 



Potato Syraying Experiments. — As the tests made in 1918 

 showed a distinct superiority in results when the 4-4-50 home- 

 made Bordeaux mixture was used, and as this substance was 

 only incidental to the real tests which were on insecticides 

 rather than fungicides, only homemade Bordeaux was used 

 this year, while the arsenates of lead, of calcium and of mag- 

 nesium were tested in combination with it. All of these ar- 

 senicals were commercial brands in the form of a dry powder. 

 The arsenate of lead contained 33 per cent arsenic oxid, the 

 arsenate of calcium about 46 per cent and the arsenate of 

 magnesium 32 to 33 per cent. The quantity used in each 

 case was that given by the manufacturer for potato spraying, 

 and was such as to provide about an equal amount of poison 

 per gallon of spray for each of the three kinds. 



As far as ease of preparation was concerned, no difference 

 between the three materials was observed, nor was there any 

 perceptible difference in the health, vigor or rate of growth 



